In the 3rd Generation Partnership Project (3GPP), a W-CDMA scheme has been standardized as a third generation cellular mobile communication system, and is in service. Furthermore, HSDPA in which communication speed is further increased has been standardized as well and is in service.
On the other hand, in 3GPP, standardization of Evolved Universal Terrestrial Radio Access (which is hereinafter referred to as “EUTRA”) has been performed as well and has started to be in service. As a downlink communication scheme for EUTRA, an Orthogonal Frequency Division Multiplexing (OFDM) scheme, which is highly resistant to multi-path interference and is suitable for high-speed transfer, is employed. Furthermore, as an uplink communication scheme, a Discrete Fourier Transform (DFT)-spread OFDM scheme for Single Carrier-Frequency Division Multiple Access (SC-FDMA) that is capable of reducing a Peak to Average Power Ratio (PAPR) for a transmission signal is employed considering the cost of and power consumption by a mobile station apparatus.
Furthermore, in 3GPP, Advanced-EUTRA that is a further advanced version of EUTRA has been started to be studied as well. It is assumed that in Advanced-EUTRA, a band up to a maximum bandwidth of 100 MHz is used in each of the uplink and the downlink, and that communication is performed to the maximum at a transfer rate of 1 Gbps or more in the downlink and at a transfer rate of 500 Mbps or more in the uplink.
It is considered that in Advanced-EUTRA, multiple bands that are compatible with EUTRA are aggregated in such a manner that the mobile station apparatus for EUTRA can be accommodated as well, and thus a maximum band of 100 MHz is realized. Moreover, in Advanced-EUTRA, one band of 20 MHz or less for EUTRA is referred to as a Component Carrier (CC). The component carrier is also referred to a cell. Furthermore, the aggregating of bands of 20 MHz or less is referred to as Carrier Aggregation (CA) (NPL 1).
Furthermore, in Advanced-EUTRA, it is considered that the Carrier Aggregation is performed within a frequency or between frequencies in a Macro Cell and a Small Cell within a range of the Macro Cell. Being within the range of the Macro Cell includes frequencies being different from each other. In NPL 2, it is proposed that in communication between a base station apparatus and the mobile station apparatus at the time of the Carrier Aggregation in the Macro Cell and the Small Cell, control information (Control-Plane Information) is transmitted in the Macro Cell and user information (User-Plane Information) is transmitted in the Small Cell. The Carrier Aggregation in the Macro Cell and the Small Cell that is illustrated in NPL 2 is also referred to as Dual Connect (or Dual Connectivity).
Moreover, it is also considered that, with the Dual Connect, information on the same radio bearer (RB) is transmitted from the base station apparatus in the Macro Cell and the base station apparatus in the Small Cell to the mobile station apparatus and the information on the same radio bearer (RB) is transmitted from the mobile station apparatus to the base station apparatus in the Macro Cell and the base station apparatus in the Small Cell. Moreover, control in which the base station apparatus and the mobile station apparatus transmit and receive the information on the same radio bearer through different base station apparatuses is referred to as Bearer Split.